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// SPDX-License-Identifier: BSD-3-Clause
#include "crc.h"
namespace voltronic {
static const u16 table[16] = {
0x0000, 0x1021, 0x2042, 0x3063,
0x4084, 0x50A5, 0x60C6, 0x70E7,
0x8108, 0x9129, 0xA14A, 0xB16B,
0xC18C, 0xD1AD, 0xE1CE, 0xF1EF
};
static inline bool is_reserved(u8 b) {
return b == 0x28 || b == 0x0D || b == 0x0A;
}
CRC crc_read(const u8* buf) {
CRC crc = 0;
crc |= (u16) buf[0] << 8;
crc |= (u16) buf[1];
return crc;
}
void crc_write(CRC crc, u8* buffer) {
if (buffer != nullptr) {
buffer[0] = (crc >> 8) & 0xFF;
buffer[1] = crc & 0xFF;
}
}
CRC crc_calculate(const u8* buf, size_t bufSize) {
CRC crc = 0;
if (bufSize > 0) {
u8 byte;
do {
byte = *buf;
crc = table[(crc >> 12) ^ (byte >> 4)] ^ (crc << 4);
crc = table[(crc >> 12) ^ (byte & 0x0F)] ^ (crc << 4);
buf += 1;
} while (--bufSize);
byte = crc;
if (is_reserved(byte))
crc += 1;
byte = crc >> 8;
if (is_reserved(byte))
crc += 1 << 8;
}
return crc;
}
}
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